JSON formatter and validator
Indent JSON so it can be read, or minify it for shipping — and find out exactly where it breaks.
- Runs on your device — the file is never sent anywhere
- No sign-up, no watermarks, no daily quotas
- Free, with no limit on how often you use it
How it works
Most JSON formatters are websites you paste data into — which means pasting API keys, customer records or internal payloads into someone else's server. This one parses the file in the page. Nothing is transmitted, and nothing is logged, which matters more for configuration and API data than almost any other file type.
Indented or minified
Indented output adds two-space indentation and line breaks, which is what you want when reading a file or reviewing it in a pull request. Minified output strips every unnecessary byte, which is what you want when shipping it over a network. The data is identical either way.
Validation comes free
If the file will not parse, you get the parser's own error message, which names the position where the problem is. The usual culprits are a trailing comma after the last item, single quotes instead of double, or an unescaped character inside a string.
What formatting does not change
Key order is preserved as written. Numbers are re-emitted in their canonical form, so very large integers beyond JavaScript's safe range can lose precision — that is a limitation of the language, not of the formatter, and it affects every JavaScript-based tool equally.
JSON formatter and validator — questions
Is my JSON sent to a server?
No. It is parsed inside the page by your own browser. Nothing is transmitted or stored.
What happens if my JSON is invalid?
You get the parser's error message, including where the problem occurs, so you can find it in the source file.
Does formatting change my data?
No. Only whitespace changes. Keys keep their order and values are unchanged.